The National Federation of Associations for Reception and Social Reintegration (FNARS) and the French Institute for Public Health Surveillance (InVS) conducted a study on the health of people engaged in prostitution, using an action-research approach, with the aim of helping to improve medical and social care for this population. A total of 251 people participated in the health-social component of the study, conducted within community organizations, and 78 people participated in the medical component, conducted at Centers for Information, Screening, and Diagnosis of Sexually Transmitted Infections (Ciddist) or Family Planning and Education Centers (CPEF). More than three-quarters (78%) of the respondents were foreign nationals, and two-thirds were women. The respondents faced multiple factors of social vulnerability (social isolation, housing conditions, residency status, health insurance coverage). More than half of the respondents reported being in fair, poor, or very poor health, a proportion significantly higher than that of the general population. Women exhibited particular vulnerability in gynecological and obstetric health (low rates of cervical cancer screening, low use of oral contraception, and high rates of abortion). Transgender individuals were heavily affected by HIV, with a reported prevalence of 44%. The study population, which was vulnerable in terms of mental health, was particularly exposed to physical and psychological violence. Given the specific services involved, this study is not representative of the entire population of people engaged in prostitution in France. Nevertheless, it allows for the formulation of recommendations regarding prevention and access to rights and healthcare. (R.A.)